Endangered: Leatherback Sea Turtle

Dermochelys coriacea

A Singular Sea Turtle...More than six feet long, weighing as much as 1400 pounds (636 kg), leatherbacks are the world's largest pelagic (ocean-going) turtles. They are also the only sea turtle with a soft, rubbery shell. (All others have hard, bony-plated shells.) Leatherbacks have special adaptations that allow them to eliminate waste gases through their skin, so they can stay under water for extraordinarily long periods. Inside their bodies, they actually convert salt water to fresh water, ingesting the sea water around them and excreting the salt. Their bodies are insulated by a thick layer of fat -- another adaptation that is unique among turtles to leatherbacks.

Any leatherback that survives to adulthood has overcome enormous odds. Females may lay more than 100 eggs in a nest, but many of these are eaten by predators (including humans) before they hatch. Of the hatchlings that do make it out of the nest, the vast majority are eaten by predators (primarily gulls and other birds) on the beach or in the ocean. A nest of 100 eggs will probably produce no more than one or two adults.

After leatherback females lay their eggs, they immediately return to the sea. The moon's reflection on the water may help them find their way but artificial lights disorient them and can cause them to crawl the wrong way and die of exhaustion and dehydration. Lights can also mislead hatchling leatherbacks when they begin their frantic rush across the beach to the surf. In the southeastern U.S., coastal communities are encouraged to turn off exterior lights during the hatching period so the hatchlings can find their way home.

Leatherbacks have been on the Endangered Species List since 1970. But because they are so difficult to count, it's impossible to determine how leather-back populations are affected by loss of nesting sites, plastic ingestion, egg poaching, and commercial fisheries. Before any conclusions are reached, additional research is required.

...With Multiple Threats

They are strong and graceful swimmers, with powerful front flippers. They spend almost all of their lives at sea, swimming into shallow bays and estuaries to court and mate. The only time leatherbacks come ashore is to lay their eggs, which they do only on sandy, undisturbed beaches.

Leatherbacks are among the most wide-ranging of all vertebrates. They are found in oceans and seas around the world, in habitats ranging from tropical to subarctic. They migrate over long distances, which makes them hard to track and even harder to count. Only the females come ashore and then for just a couple of hours while they lay their eggs. This gives scientists a chance to count and tag them. Current estimates put the worldwide female population at about 100,000. Since males don't come ashore at all, it's virtually impossible to estimate their numbers.

Leatherbacks build their nests on remote stretches of sandy beach. Loss of these coastal nesting habitats is one of the primary threats to leatherback survival.

Fishing is another. Leatherbacks get caught in commercial shrimp nets and suffocate. Turtle Excluder Devices, called TEDs, have been built into some nets that let captured animals escape, but shrimpers complain that TEDs cut down on their catch size. It has been estimated that 11,000 marine turtles are caught in nets every year. Many of them are leatherbacks.

Leatherback eggs are harvested in Malaysia for food, and in some parts of Asia, the turtle is hunted for its oil and flesh.

And then there's the plastics problem. Leather-backs eat twice their weight each day. Their primary food is jellyfish. Unfortunately, they can't distinguish between jellyfish and clear plastic debris, such as sandwich bags. In recent studies, nearly half of all leatherbacks examined had plastic or cellophane in their stomachs. It's not known how much plastic it takes to kill a leatherback, but two facts are clear: no animal can digest plastic, and the amount of plastic in the oceans is increasing drastically every day.